Connected: An Internet Encyclopedia
RFC 1446 - 1.5. Mechanisms

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### 1.5. Mechanisms

The security protocols defined in this memo employ several types of mechanisms in order to realize the goals and security services described above:

- In support of data integrity, a message digest algorithm is required. A digest is calculated over an appropriate portion of a SNMPv2 message and included as part of the message sent to the recipient.

- In support of data origin authentication and data integrity, the portion of a SNMPv2 message that is digested is first prefixed with a secret value shared by the originator of that message and its intended recipient.

- To protect against the threat of message delay or replay, (to an extent greater than can occur through normal operation), a timestamp value is included in each message generated. A recipient evaluates the timestamp to determine if the message is recent. This protection against the threat of message delay or replay does not imply nor provide any protection against unauthorized deletion or suppression of messages. Other mechanisms defined independently of the security protocol can also be used to detect message replay (e.g., the request-id [2]), or for set operations, the re-ordering, replay, deletion, or suppression of messages (e.g., the MIB variable snmpSetSerialNo [14]).

- In support of data confidentiality, a symmetric encryption algorithm is required. An appropriate portion of the message is encrypted prior to being transmitted to its recipient.

The security protocols in this memo are defined independently of the particular choice of a message digest and encryption algorithm - owing principally to the lack of a suitable metric by which to evaluate the security of particular algorithm choices. However, in the interests of completeness and in order to guarantee interoperability, Sections 1.5.1 and 1.5.2 specify particular choices, which are considered acceptably secure as of this writing. In the future, this memo may be updated by the publication of a memo specifying substitute or alternate choices of algorithms, i.e., a replacement for or addition to the sections below.

1.5.1. Message Digest Algorithm
1.5.2. Symmetric Encryption Algorithm

Next: 1.5.1. Message Digest Algorithm

Connected: An Internet Encyclopedia
RFC 1446 - 1.5. Mechanisms